Donor-Acceptor Materials Exhibiting Thermally Activated Delayed Fluorescence Using a Planarized N-Phenylbenzimidazole Acceptor

Article abstract of DOI:10.1021/acs.joc.9b02283

An N-phenylbenzimidazole constrained in a coplanar fashion with a methylene tether (IMAC) was designed and used to prepare a series of emitters exhibiting thermally activated delayed fluorescence (TADF). Four novel TADF emitters using 9,9-dimethylacridine

Full text of DOI:10.1021/acs.joc.9b02283

Article
Cite This: J. Org. Chem. XXXX, XXX, XXX−XXX
pubs.acs.org/joc
Donor−Acceptor Materials Exhibiting Thermally Activated Delayed
Fluorescence Using a Planarized N‑Phenylbenzimidazole Acceptor
§
§
,†,‡
,§
Ethan R. Sauve,
́
Jaesuk Paeng, Shigehiro Yamaguchi,*
and Zachary M. Hudson*
†Department of Chemistry, Graduate School of Science, Integrated Research Consortium on Chemical Sciences (IRCCS), Nagoya
University, Furo, Chikusa, Nagoya 464-8602, Japan
‡
Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo, Chikusa, Nagoya 464-8602, Japan
§
Department of Chemistry, The University of British Columbia, 2036 Main Mall, Vancouver, British Columbia V6T 1Z1, Canada
*
S Supporting Information
ABSTRACT: An N-phenylbenzimidazole constrained in a coplanar
fashion with a methylene tether (IMAC) was designed and used to
prepare a series of emitters exhibiting thermally activated delayed
fluorescence (TADF). Four novel TADF emitters using 9,9-
dimethylacridine, phenoxazine, phenothiazine, and bis(di-p-
tolylamino)carbazole as the donor group were designed and
synthesized using IMAC as the acceptor. Additionally, two deep-
blue fluorescent emitters were prepared with carbazole and
tercarbazole as the donor moieties. The twisted conformation
between donor and acceptor in these molecules resulted in effective spatial separation of the HOMO and LUMO and small
singlet−triplet energy gaps. Crystallographic properties, electronic structures, thermal stabilities, photophysical properties, and
energy levels were studied systematically. Ultimately, these findings provide a promising opportunity for the design and
synthesis of highly efficient TADF materials based on IMAC derivatives.
INTRODUCTION
transfer character, including broad emission bands and large
Stokes shifts.
More recently, several studies have demonstrated that
molecular rigidification can lead to narrower emission spectra,
higher quantum yields and enhanced stability in luminescent
■
(
(
The discovery of thermally activated delayed fluorescence
TADF) has revolutionized organic light-emitting diode
OLED) technology, enabling the fabrication of OLEDs with
1
00% internal quantum efficiencies using purely organic
1
−5
materials, primarily as a result of suppressed vibrational
emitters.
Capable of converting triplet excitons to singlets
18,19
motion.
For example, Yamaguchi and co-workers utilized
through reverse intersystem crossing (RISC), TADF com-
pounds have attracted significant recent attention as robust,
efficient, and scalable emissive materials.
tions in OLEDs have been the primary driver of TADF
research to date, these materials have also found use in
fluorescence lifetime imaging
achieve efficient RISC, TADF materials are typically designed
to minimize the energy difference between the lowest triplet
the idea of structural constraint to create an extremely
6
−10
photostable phosphole-based dye for multiple-acquisition
Though applica-
20,21
stimulated emission depletion (STED) imaging.
Further-
more, they synthesized a series of planarized 9-phenyl-
anthracene derivatives, in which the planar and rigid structure
induced effective π-conjugation and reduced the nonradiative
decay process from the excited state, resulting in red-shifted
1
1,12
13
and oxygen sensing. To
absorptions, increased molar absorption coefficients, and
(
T ) and lowest singlet (S ) excited states, termed ΔE .
22−26
1
1
ST
intense fluorescence.
Hatakeyama and co-workers have
While T states are substantially lower in energy than their
1
also leveraged an organoboron compound, possessing two
nitrogen atoms, in a rigid polycyclic aromatic framework to
S counterparts in the vast majority of molecules, a small ΔE
1
ST
can be achieved by minimizing the Pauli repulsion (or
exchange energy) between ground and excited state electrons.
In practical terms, this is commonly achieved by designing
materials with minimal overlap between their HOMO and
LUMO, such that the electrons of the frontier orbitals will
occupy different regions of space when the material is excited.
This is often obtained by the coupling of donor and acceptor
4,18,19
produce ultrapure blue TADF emitters in this fashion.
Deep blue or violet TADF emitters pose a particular
synthetic challenge, in light of the large Stokes shifts typically
caused by the common donor−acceptor conformation of
27−33
TADF materials.
To realize deep blue emission a wide
energy gap >2.75 eV is required; therefore, an electron
14−16
units in a twisted conformation,
sometimes using steric
Special Issue: Functional Organic Materials
Received: August 21, 2019
bulk to ensure that the π systems of the donor and acceptor
17
remain orthogonal. This type of conformation also results in
emitters with large transition dipoles and significant charge-
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.joc.9b02283
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
acceptor with a shallow LUMO is ideal. Imidazole and
benzimidazole are attractive electron acceptors for this reason,
and many imidazole-based blue fluorescent emitters have been
reported with PLQYs near unity and high device efficien-
donor-π-acceptor materials using six different donor moieties
commonly used in organic electronics, including phenoxazine
(PXZ), phenothiazine (PTZ), 9,9-dimethylacridan (ACR), and
carbazole (CZ). Several of these molecules exhibit TADF with
deep blue to green emission colors, and quantum yields of up
to 0.99. These compounds should find application in the
emitting layer of OLEDs, either as the emitter or as ambipolar
host materials.
3
4−37
cies.
However, there are few reports in which imidazole-
containing compounds have exhibited TADF. In 2018, Wang
3
8
and co-workers reported highly efficient green organic light
emitting diodes with phenanthroimidazole-based TADF
emitters, and shortly after Kido and co-workers reported a
series of imidazo[1,2-f ]phenanthridine-based sky-blue TADF
RESULTS AND DISCUSSION
3
9
■
compounds.
Synthesis and Solid-State Structure. Synthesis of the
IMAC acceptor fragment began with a double Grignard
addition to methyl anthranilate using MeMgBr to give tertiary
alcohol 1, which was then protected using 1,1′-carbon-
yldiimidazole to give carbamate 2 (Scheme 1). Nucleophilic
aromatic substitution of o-nitrofluorobenzene with 2 was then
used to obtain 3 in 70% yield. Hydrolysis of the carbamate was
achieved in the presence of NaOH, followed by electrophilic
aromatic substitution in the presence of H PO to form the
Herein we report the design of a planarized 1-phenyl-
benzimidazole chromophore that has been linked via a
methylene bridge at the 2 and 7 positions of the phenyl ring
and the benzimidazole, respectively (Figure 1). This fused
3
4
nitrosylated acridine 5. Reduction of the nitro group to a
primary amine was achieved using Pd/C and hydrazine,
yielding 6 quantitatively and giving a planarized, ortho-diamine
that can be used to prepare benzimidazoles from a variety of
aldehydes. Finally, a series of phenylaldehyde-linked donors
were coupled with 6 via I -mediated intramolecular C−H
2
4
0
amidation
to synthesize the target donor-π-acceptor
Figure 1. Optimized structure for 1-phenyl-1H-benzo[d]imidazole
compounds in yields ranging from 56% to 65%. The identity
1
13
1
(left) and 6,6-dimethyl-6H-imidazo[4,5,1-de]acridine (right).
of final compounds was confirmed by H and C{ H} NMR,
as well as high resolution mass spectrometry (HRMS).
Single crystals of PXZ-IMAC, PTZ-IMAC, ACR-IMAC,
and CZ-IMAC were obtained from a mixture of CH Cl and
imidazole/acridine chromophore (IMAC, formally 6,6-dimeth-
yl-6H-imidazo[4,5,1-de]acridine) was then used to prepare
2
2
Scheme 1. Synthesis of IMAC Compounds
B
DOI: 10.1021/acs.joc.9b02283
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Article
Figure 2. Crystal structures of (A) PXZ-IMAC, (B) PTZ-IMAC, (C) ACR-IMAC, and (D) CZ-IMAC depicted with 50% thermal ellipsoids.
Hydrogen atoms and cocrystallized solvent molecules omitted for clarity. Selected bond lengths (Å): PXZ-IMAC N1−C16 1.319(2), N2−C16
1
1
.397(3), N3−C20 1.437(3); PTZ-IMAC N1−C16 1.318(3), N2−C16 1.396(2), N3−C20 1.437(2); ACR-IMAC N1−C16 1.326(3), N2−C16
.400(3), N3−C20 1.436(3); CZ-IMAC N1−C16 1.318(3), N2−C16 1.392(2), N3−C20 1.428(2). Selected torsion angles (deg): PXZ-IMAC
N1−C16−C17−C18 135.0(2), C19−C20−N3−C23 98.7(2); PTZ-IMAC N1−C16−C17−C18 57.5(3), C19−C20−N3−C23 69.3(2); ACR-
IMAC N1−C16−C17−C18 134.2(2), C19−C20−N3−C23 97.6(3); CZ-IMAC N1−C16−C17−C18 52.5(3), C19−C20−N3−C23 120.0(2).
−
5
Figure 3. UV−vis spectra measured in CH Cl at 1 × 10 M and PL spectra measured in toluene solution at 0.05 to 0.15 optical density for (A)
2
2
PXZ-IMAC, (B) PTZ-IMAC, (C) ACR-IMAC, (D) CZ-IMAC, (E) TerCZ-IMAC, and (F) TolCZ-IMAC. Photographs of the series of
compounds in toluene (G) and as 10 wt % films in DPEPO (H) irradiated with 365 nm light.
hexanes by slow evaporation (Figure 2). The solid-state
structures indicate the donor groups are twisted with respect to
the phenyl ring giving very large dihedral angles of 81.3 and
CZ-IMAC derivative is the only compound to cocrystallize
with solvent (CH Cl ).
2
2
Photophysical and Electrochemical Properties. UV−
vis absorption and photoluminescence (PL) spectra of this
series of compounds in toluene solution (1 × 10− M) are
shown in Figure 3. Absorption maxima are between 293 and
8
2.4° for PXZ-IMAC and ACR-IMAC, respectively. PTZ-
5
IMAC and CZ-IMAC have more moderated twisting with
dihedral angles of 69.3 and 60.0°, respectively. Such twisted
structures typically result from the steric repulsion of hydrogen
atoms in the phenyl and heteroaromatic units. Further, it
results in effective spatial separation of the HOMO and
308 nm, and all compounds have broad, featureless emission
spectra consistent with a charge-transfer excited state. On the
basis of TD-DFT calculations we attribute the lowest energy
transition in all cases to the HOMO to LUMO transition. TD-
DFT predicts PXZ-IMAC, PTZ-IMAC, ACR-IMAC, and
TolCZ-IMAC to all have lowest energy transitions above 395
nm, significantly higher than the CZ-IMAC or TerCZ-IMAC
derivatives (Table S1). However, the oscillator strengths are
calculated to be 0.0004 (extremely low) for the PTZ-IMAC
LUMO and reduction of ΔE . There also exists a moderate
ST
twist between the imidazole plane and the phenyl ring resulting
in dihedral angles between 52.5−57.5°. PXZ-IMAC, PTZ-
IMAC, and ACR-IMAC all pack in the P21/c space group,
̅
while CZ-IMAC packs in the P1 space group. Additionally, the
C
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The Journal of Organic Chemistry
Article
Figure 4. PL decay curves for (A) PXZ-IMAC, (B) PTZ-IMAC, (C) ACR-IMAC, (D) CZ-IMAC, (E) TerCZ-IMAC, and (F) TolCZ-IMAC
doped in 10 wt % DPEPO films at 300 K.
Table 1. Photophysical Properties of IMAC Compounds
a
b
,
c
b
c
b
c
c
entry
λmax,abs
λmax,em
Φ solution /solid
CIE
τp (ns)
τd (μs)
PXZ-IMAC
PTZ-IMAC
ACR-IMAC
CZ-IMAC
TerCZ-IMAC
TolCZ-IMAC
298
303
293
293
294
308
502/485
515/469
450/449
394/405
401/409
496/491
0.31/0.71
0.08/0.05
0.34/0.51
0.99/0.85
0.94/0.61
0.85/0.45
(0.23, 0.43)
(0.27, 0.44)
(0.15, 0.12)
(0.16, 0.03)
(0.16, 0.04)
4.2, 13.8
2.1, 10.1
5.7, 14.2
1.9, 28.2
2.9, 17.2
4.4, 13.1
1390
228
127
−
−
1194
(0.21, 0.39)
a
b
c
Measured in CH Cl Measured in degassed toluene with an optical density between 0.05 and 0.15. Measured as films doped in DPEPO at 10 wt
2
2.
%
under vacuum. DPEPO: Bis[2-(diphenylphosphino)phenyl] ether oxide.
and 0.0002 for the ACR-IMAC derivatives, slightly higher at
IMAC, and TolCZ-IMAC showed clear long-lived exponential
decays at 300 K. PXZ-IMAC exhibits a two-component short
lifetime of 4.2 and 13.8 ns (Figure S32) and a long lifetime of
1390 μs, and these are 2.1 ns, 10.1 ns and 228 μs for PTZ-
IMAC. ACR-IMAC and TolCZ-IMAC had lifetimes of 5.7 ns,
14.2 ns, 127 μs and 4.4 ns, 13.1 ns, 1194 μs, respectively. The
two-component nature of the short lifetimes is likely a result of
the film consisting of both an IMAC emitter and DPEPO host;
thus, there is possibility for direct excitation of the emitter as
well as for energy transfer from the host to emitter. The short
lifetime component was attributed to relaxation from S to S ,
0
0
.0142 for the PXZ-IMAC derivative and much higher at
.2792 for the TolCZ-IMAC derivative, consistent with
apparent intensities observed in their experimental spectra.
All compounds showed strong positive solvatochromism in the
fluorescence spectra, with significant red shifts in polar relative
to nonpolar solvents (Figure S31). The effect was most
pronounced for TolCZ-IMAC and PXZ-IMAC, with red shifts
−
1
−1
of 176 (5861 cm ) and 157 nm (5510 cm ) going from
hexanes to MeCN, respectively. CZ-IMAC had the least
dramatic shift of 3676 cm− going from 378 to 439 nm as the
solvent polarity was increased from hexanes to MeCN. For
simplicity Stokes shifts discussed in this paper are the apparent
shifts from the largest absorption band to the emission
maxima. It has previously been reported that chromophores
containing N-phenylphenothiazine can adopt two conforma-
tions, termed quasi-axial and quasi-equatorial, differing in the
relative orientations of the phenothiazine moiety and the
1
1
0
and the delayed component was assigned to thermal up-
conversion of excitons from T to S , followed by relaxation
1
1
from S to S . PL decay curves were measured for PXZ-IMAC,
1
0
PTZ-IMAC, ACR-IMAC, and TolCZ-IMAC at 77 K, and in
all cases the delayed component was suppressed, confirming
the thermal dependence (Figure S33). Time-resolved emission
spectra of all compounds were obtained in 2-MeTHF solution
measured at 77 K (Figure S34) in order to determine the
4
1−44
phenyl ring.
Such conformers often result in dual
emission properties, as is observed in PTZ-IMAC, with
peaks at ∼400 and ∼530 nm and may also explain its low
photoluminescence quantum yield (PLQY, Φ).
singlet−triplet gap for each compound. ΔE was also
ST
determined for doped films at room temperature by using an
approximate relationship among ΔE , k
, and k (Table
and Hatakeyama. We also
ST
TADF
F
5
,45
19
In order to probe the delayed fluorescence behavior of the
series of compounds, transient photoluminescence decay
curves for each compound doped in bis[2-(diphenylphos-
phino)phenyl] ether oxide (DPEPO) films (10 wt %) were
measured at room temperature. DPEPO was chosen since it is
a large band gap material commonly used to host blue TADF
materials in OLEDs. As shown in Figure 4 and summarized in
Table 1, the doped films of PXZ-IMAC, PTZ-IMAC, ACR-
S2), as described by Adachi
note that the delayed fluorescence lifetimes for TolCZ-IMAC
and PXZ-IMAC are much longer than those of PTZ-IMAC
and ACR-IMAC, while their solid-state quantum yields are
significantly higher (Table 1). Films of CZ-IMAC and TerCZ-
IMAC had no observable delayed component under these
conditions, consistent with DFT calculations indicating these
compounds possess a larger ΔEST (vide infra).
D
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Table 2. Calculated and Experimental Electronic Properties of the Series of IMAC Compounds
HOMO (eV)
LUMO (eV)
Eg (eV)
ΔEST (eV)
E1/2ox
a
E1/2red
a
calc.
exp.
b
calc.
exp.
b
calc.
exp.
c
calc.
exp.
,
de
compound
PXZ-IMAC
PTZ-IMAC
ACR-IMAC
CZ-IMAC
TerCZ-IMAC
TolCZ-IMAC
0.28
0.31
0.51
0.49
−
−2.52
−2.52
−2.52
−2.54
−2.45
−2.48
−4.90
−5.23
−5.15
−5.63
−5.43
−5.08
−5.11
−5.31
−5.29
−5.61
−5.01
−1.41
−1.40
−1.34
−1.33
−1.54
−2.28
−2.28
−2.28
−2.26
−2.35
−2.32
2.77
3.12
3.06
3.65
3.43
2.93
2.92
3.32
3.15
3.41
3.35
2.92
0.03
0.04
0.01
0.60
0.31
0.17
0.29/0.27
0.25/0.76
0.21/0.25
−/0.71
−/0.66
0.27/0.28
f
0.21
−4.71
−1.33
0/+
a
In DMF relative to FeCp0/+. Calculated from E1/2 relative to the FeCp HOMO level (−4.80 eV). E was determined from the intersection
b
ox
c
g
d
point of the normalized emission and absorption spectra. Determined using an approximate relationship among ΔE , k
, and k in the same
ST TADF
F
e
manner as reported by Adachi in refs 45 and 5 and by Hatakeyama in ref 19. For additional information see Table S2. Determined from the high
−
5
f
energy band edge of the phosphorescence spectrum in 2-MeTHF at 10 M at 77 K. Calculated from the LUMO level and the optical energy gap,
E .
g
Figure 5. Optimized structures, and HOMO and LUMO distributions for the series of IMAC-containing compounds.
The electrochemical properties and energy levels of these
compounds were investigated by cyclic voltammetry in DMF
using a conventional three electrode system. All compounds
undergo reduction at approximately −2.50 eV (Table 2 and
Figure S35) relative to the FeCp0 redox couple, arising from
the IMAC unit. These are in reasonable agreement with similar
donor−acceptor compounds containing benzimidazole. The
LUMO energy levels of the compounds were calculated to be
approximately −1.4 eV. TolCZ-IMAC had the lowest
oxidation potential at 0.21 eV, followed closely by PXZ-
IMAC at 0.28 eV and PTZ-IMAC at 0.31 eV. CZ-IMAC and
ACR-IMAC had significantly higher oxidation potentials at
31+G(d) method/basis set in Gaussian 09 software were
performed to obtain insight into the molecular conformation
and electronic structures of these emissive materials. The
calculation results, showing the optimized structure and
HOMO/LUMO distribution of each compound, are given in
Figure 5. Significant separation of the HOMO and LUMO is
present for all compounds, with the HOMO mainly distributed
on the donor group and the LUMO centered on the IMAC
acceptor. CZ-IMAC was an exception to this trend, with the
IMAC unit contributing significantly to the HOMO
consistent with the lack of observed delayed fluorescence for
this material. We next calculated the S and T excited state
/+
37
1
1
0
.49 and 0.51 eV, respectively. Oxidation of the TerCZ-IMAC
energies using time-dependent density functional theory (TD-
could not be achieved within the solvent window of DMF,
though a reduction peak was still observed for this compound.
Theoretical Calculations. Quantum chemical calculations
using density functional theory (DFT) with the PBE0/6-
DFT). The calculated ΔE values were <0.04 eV for PXZ-
ST
IMAC, PTZ-IMAC, and ACR-IMAC, consistent with their
apparent TADF behavior. CZ-IMAC was calculated to have
quite a large ΔEST of 0.60 eV, most likely due to the very weak
E
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Article
donating ability of the CZ donor moiety leading to substantial
overlap of the HOMO and LUMO on the IMAC fragment.
TerCZ-IMAC and TolCZ-IMAC were calculated to have gaps
of 0.31 and 0.17 eV, respectively. These values are small
enough that efficient TADF should be possible.
wire) in 0.1 M tetrabutylammonium hexafluorophosphate in DMF.
−
1
Experiments were run at a scan rate of 100 mV s in dry degassed
−
1
electrolyte solution with ∼1 mg mL of analyte.
Density Functional Theory. Calculations were performed using
51
the Gaussian 09 software package. Ground state geometries and
energies were calculated at the PBE0/6-31+G(d) level of theory. The
singlet and triplet states were calculated by the Tamm-Dancoft
approximation to time-dependent density functional theory (TD-
DFT) with the PBE0 functional at the same basis set level. Molecular
orbitals were visualized using Avogadro version 1.20 and rendered
using POV-Ray version 3.7.0.
CONCLUSIONS
■
In summary, a planarized IMAC acceptor fragment was
prepared and used to synthesize six donor-π-acceptor type
emissive materials. Four of these donor-π-acceptor molecules
exhibit TADF with deep blue to green emission color in the
solid state and photoluminescence quantum yields of up to
Synthetic Procedures. Synthesis of 4,4-Dimethyl-1,4-dihydro-
2
H-benzo[d][1,3]oxazin-2-one (2). A mixture of N,N′-carbon-
yldiimidazole (24.4 g, 150 mmol) and 2-(2-aminophenyl)propan-2-
ol (1) (18.0 g, 119 mmol) in THF (500 mL) was refluxed for 16 h.
The solvent was evaporated under reduced pressure to give a yellow
0
.85 in solution. Additionally, two fluorescent emitters were
prepared with carbazole and tercarbazole donor moieties and
quantum yields of 0.94 and 0.99, respectively. Theoretical
calculations established the donor−acceptor character of the
oil, which was redissolved in CH Cl and washed with saturated
2 2
aqueous NH Cl, 2 N HCl solution, and brine. The organic layer was
4
dried over anhydrous MgSO and concentrated to afford a yellow
molecules, as well as indicating small ΔE values for the
4
ST
1
solid. Yield = 17.8 g (85%). mp = 106.5−108.6 °C. H NMR (400
compounds that exhibited delayed fluorescence. The results
provide a promising opportunity for the design and synthesis
of highly efficient TADF materials based on IMAC derivatives.
MHz, DMSO-d ) δ 10.20 (s, 1H), 7.32−7.19 (m, 2H), 7.04 (td, J =
6
1
3
7
.6, 1.2 Hz, 1H), 6.91 (dd, J = 7.9, 1.1 Hz, 1H), 1.62 (s, 6H).
C
NMR (101 MHz, DMSO-d ) δ 150.66, 134.67, 128.61, 126.23,
6
+•
1
23.41, 122.57, 113.99, 81.32, 27.62. HRMS (EI) m/z [M ] calcd for
[C H NO ] , 177.07898; found, 177.07862; difference, −2.02
+
•
EXPERIMENTAL DETAILS
■
10 11
2
ppm.
General Considerations. All reactions and manipulations were
carried out under a nitrogen atmosphere using standard Schlenk or
glovebox techniques unless otherwise stated. Dry solvents were
obtained from Caledon Laboratories, dried using an Innovative
Technologies Inc. solvent purification system, collected under
vacuum, and stored under a nitrogen atmosphere over 4 Å molecular
sieves. All reagents were purchased from Sigma-Aldrich, Cambridge
Isotope Laboratories, Alfa Aesar or Tokyo Chemical Institute and
used as received unless otherwise stated. Syntheses of the following
Synthesis of 4,4-Dimethyl-1-(2-nitrophenyl)-1,4-dihydro-2H-
benzo[d][1,3]oxazin-2-one (3). A mixture of 2 (17.8 g, 100 mmol),
1
-fluoro-2-nitrobenzene (15.7 g, 111 mmol) and CsCO (39.1 g, 121
3
mmol) in DMF (250 mL) was heated to 95 °C for 16 h. After cooling
to room temperature, the reaction was poured into 500 mL of water
and extracted with EtOAc (5 × 100 mL). The combined organic layer
was washed with water and brine, dried over anhydrous MgSO4,
concentrated to give a bright yellow oil, and then purified through
46
silica gel column chromatography (hexanes/EtOAc 4:1, R = 0.02
compounds have been previously reported: 1, 4-(10H-phenoxazin-
f
47
44
gradient to hexanes/EtOAc 1:1) to afford a yellow solid. mp = 89.8−
1
(
0-yl)benzaldehyde, 4-(10H-phenothiazin-10-yl)benzaldehyde, 4-
1
48
9
8
1.7 °C. Yield = 21.1 g (70%). H NMR (400 MHz, DMSO-d ) δ
9H-carbazol-9-yl)benzaldehyde, 4-(9′H-[9,3′:6′,9″-tercarbazol]-9′-
6
49
49
1
.29 (dd, J = 8.2, 1.5 Hz, 1H), 7.96 (td, J = 7.7, 1.5 Hz, 1H), 7.83 (td,
yl)benzaldehyde, and 9-benzyl-3,6-diiodo-9H-carbazole. The H
13
1
J = 7.8, 1.4 Hz, 1H), 7.76 (dd, J = 7.9, 1.4 Hz, 1H), 7.47 (dd, J = 7.6,
and C{ H} nuclear magnetic resonance (NMR) spectra were
measured on a Bruker AV III HD 400 MHz spectrometer with
chloroform-d (CDCl ), methylene chloride-d (CD Cl ), benzene-d
1
1
.6 Hz, 1H), 7.22 (dtd, J = 24.3, 7.6, 1.4 Hz, 2H), 6.31 (dd, J = 8.0,
.2 Hz, 1H), 1.81 (s, 3H), 1.78 (s, 3H). C NMR (101 MHz,
1
3
3
2
2
2
6
DMSO-d ) δ 149.60, 146.94, 136.35, 135.36, 131.95, 130.58, 130.23,
(
C D ) or dimethyl sulfoxide-d (DMSO-d ) as the solvent. The
6
6
6
6
6
1
28.90, 127.74, 125.81, 123.84, 123.78, 114.60, 82.02, 28.11, 27.15.
chemical shift data are reported in units of δ (ppm) relative to residual
solvent. Absorbance measurements were made on a Cary 60
spectrometer and fluorescence measurements were made on an
Edinburgh Instruments FS5 spectrofluorometer. Absolute photo-
luminescence quantum yields were determined using an Edinburgh
Instruments SC−30 Integrating Sphere Module; toluene was used as
+•
+•
HRMS (EI) m/z [M ] calcd for [C H N O ] , 298.09536; found,
16 14
2
4
2
98.09503; difference, −1.08 ppm.
Synthesis of 2-{2-[(2-Nitrophenyl)amino]phenyl}propan-2-ol (4).
A mixture of 3 (21.0 g, 70.4 mmol) and 5% aqueous NaOH (10 g
NaOH in 200 mL water) in EtOH (300 mL) was heated to reflux for
−
5
1
6 h. The reaction mixture turned from light yellow to dark red. The
the solvent and spectra obtained at approximately 10 M unless
otherwise stated. Photoluminescence decay characteristics of the film
samples were investigated under vacuum conditions using an
Edinburgh Instruments FS5 spectrofluorometer and SC-80 sample
holder. The fast decay component was recorded using time-correlated
single photon counting in conjunction with a 313 nm EPLED
excitation source, while the slow decay component was recorded
using multichannel scaling with a pulsed Xe flash lamp source. Low
temperature time-resolved emission spectra were measured on a
Horiba PTI QM-400 spectrometer equipped with a Continuum
PL8000 ns YAG laser, operating at 355 nm, 10 Hz, and 1−2 mJ/
pulse. Mass spectra were recorded on a Kratos MS-50 instrument
using electron impact ionization. Melting points (mp) were
determined using a Barnstead Electrotherm 1001D/1001 Mel-Temp
capillary melting point apparatus equipped with a Fluke 51-II digital
thermometer.
solvent was partially removed under reduced pressure before the
mixture was poured into 500 mL of water, sonicated for 15 min, and
the resulting bright orange powder collected by vacuum filtration.
Yield = 12.4 g (64%). mp = 129.5−131.0 °C. H NMR (400 MHz,
DMSO-d ) δ 10.06 (s, 1H), 8.05 (dd, J = 8.5, 1.4 Hz, 1H), 7.85 (dt, J
1
6
= 7.6, 1.1 Hz, 1H), 7.53−7.45 (m, 1H), 7.29−7.15 (m, 2H), 7.10−
1
3
6.93 (m, 2H), 1.58 (s, 6H). C NMR (101 MHz, DMSO-d
135.51, 135.05, 133.04, 132.86, 131.67, 129.04, 127.10, 125.44,
) δ
6
+•
123.96, 122.80, 118.89, 116.16, 36.24, 31.40. HRMS (EI) m/z [M ]
+•
calcd for [C15
2.03 ppm.
H N O ] , 272.11609; found, 272.11664; difference,
16 2 3
Synthesis of 9,9-Dimethyl-4-nitro-9,10-dihydroacridine (5). A
suspension of 4 (12.4 g, 45.5 mmol) in H PO (200 mL) was stirred
3
4
for 16 h. The reaction mixture turned from orange to dark red. The
mixture was poured into water (500 mL) and the resulting bright red
Electrochemical Methods. Cyclic voltammograms were re-
corded using a BASi Epsilon Eclipse potentiostat at room temperature
using a standard three-electrode configuration (working electrode: 3
mm diameter glassy carbon; reference electrode: RE-5B Ag/AgCl
electrode in saturated aqueous KCl (BASi Inc.), referenced externally
powder collected by vacuum filtration. Yield = 9.7 g (84%). mp =
1
134.1−135.6 °C. H NMR (400 MHz, DMSO-d ) δ 10.05 (s, 1H),
6
8.04 (dd, J = 8.5, 1.5 Hz, 1H), 7.83 (dt, J = 7.5, 1.1 Hz, 1H), 7.48 (dd,
J = 7.8, 1.3 Hz, 1H), 7.27−7.15 (m, 2H), 7.05 (ddd, J = 8.4, 7.1, 1.5
Hz, 1H), 6.99 (dd, J = 8.5, 7.5 Hz, 1H), 1.56 (s, 6H). 1 C NMR (101
3
50
to ferrocene/ferrocenium (0.543 V in DMF); counter electrode: Pt
MHz, DMSO-d ) δ 135.51, 135.03, 133.01, 132.85, 131.64, 129.04,
6
F
DOI: 10.1021/acs.joc.9b02283
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
+
•
+•
1
27.10, 125.42, 123.94, 122.80, 118.88, 116.14, 36.22, 31.36. HRMS
HRMS (EI) m/z [M ] calcd for [C H N S ] , 507.17692; found,
34 25 3 1
+•
+•
(
EI) m/z [M ] calcd for [C H N O ] , 254.10553; found,
507.17579; difference, −2.22 ppm.
1
5
14
2
2
2
54.10452; difference, −3.96 ppm.
Synthesis of 9,9-Dimethyl-9,10-dihydroacridin-4-amine (6). A
mixture of 5 (143 mg, 0.562 mmol) in EtOH (5 mL) was cooled to 0
C and placed under a flow of N gas. Pd/C (6 mg, 0.06 mmol) was
Synthesis of 1-[4-(9,9-Dimethylacridin-10(9H)-yl)phenyl]-6,6-di-
methyl-6H-imidazo[4,5,1-de]acridine (ACR-IMAC). A mixture of 5
(100 mg, 0.446 mmol) and 4-(9,9-dimethylacridin-10(9H)-yl)-
benzaldehyde (154 mg, 0.491 mmol) in EtOH (10 mL) was refluxed
for 16 h. The solvent was evaporated under reduced pressure to give a
°
2
added to the stirred solution followed by very slow addition of N H .
2
4
The mixture was stirred for 30 min then slowly allowed to warm to
room temperature (care was taken to ensure the reaction vessel was
not overpressurizing) followed by heating to 50 °C. After 2 h the
reaction was cooled to room temperature and subsequently filtered
using EtOH to rinse. The filtrate was collected and concentrated to
give a black solid. Yield = 123 g (99%). mp = 108.2−110.6 °C. H
NMR (400 MHz, DMSO-d ) δ 7.80 (s, 1H), 7.34 (d, J = 7.8 Hz, 1H),
yellow oil, which was redissolved in CH
sequential addition of iodine (135 mg, 0.532 mmol) and K
mg, 1.34 mmol). The reaction mixture was stirred at reflux
temperature for the 16 h. Upon completion of the reaction, it was
Cl
2
2
(10 mL), followed by the
CO (185
2
3
quenched with 5% Na
(10 mL × 3). The combined organic layer was washed with brine (20
mL), dried over anhydrous MgSO , concentrated, and then purified
through silica gel column chromatography (CH Cl , R = 0.2) to
S O (20 mL) and then extracted with CH Cl
2 2 3 2 2
1
6
4
7.07 (t, J = 7.5 Hz, 1H), 6.94 (dd, J = 8.0, 1.3 Hz, 1H), 6.82 (t, J = 7.5
2
2
f
Hz, 1H), 6.70 (d, J = 7.7 Hz, 1H), 6.63 (t, J = 7.7 Hz, 1H), 6.53 (dd, J
afford an off white solid. Yield = 144 mg (63%). X-ray quality crystals
were obtained from the slow evaporation of a solution of ACR-IMAC
1
3
=
7.6, 1.4 Hz, 1H), 4.87 (s, 2H), 1.48 (s, 6H). C NMR (101 MHz,
1
DMSO-d ) δ 139.07, 133.30, 128.14, 128.10, 126.31, 125.53, 125.14,
in CH
methylene chloride-d
2
Cl
2
/hexanes. mp = 246.5−247.6 °C. H NMR (400 MHz,
6
1
19.82, 119.41, 113.78, 113.69, 112.60, 35.64, 30.74. HRMS (EI) m/z
2
) δ 8.05−7.92 (m, 2H), 7.55 (ddd, J = 12.9, 7.8,
+
•
+•
[
M ] calcd for [C H N ] , 224.13135; found, 224.13112;
1.3 Hz, 2H), 7.49−7.43 (m, 2H), 7.40 (dd, J = 7.7, 1.6 Hz, 2H),
7.35−7.19 (m, 3H), 7.13 (td, J = 7.6, 1.3 Hz, 1H), 7.01 (ddd, J = 8.6,
7.3, 1.5 Hz, 1H), 6.95 (ddd, J = 8.3, 7.2, 1.6 Hz, 2H), 6.87 (td, J = 7.4,
1.3 Hz, 2H), 6.36 (dd, J = 8.2, 1.3 Hz, 2H), 1.68 (s, 6H), 1.61 (s,
1
5
16
2
difference, −1.00 ppm.
Synthesis of 10-[4-(6,6-Dimethyl-6H-imidazo[4,5,1-de]acridin-1-
yl)phenyl]-10H-phenoxazine (PXZ-IMAC). A mixture of 5 (100 mg,
1
3
0
0
.446 mmol) and 4-(10H-phenoxazin-10-yl)benzaldehyde (141 mg,
.491 mmol) in EtOH (10 mL) was refluxed for 16 h. The solvent
6H). C NMR (101 MHz, methylene chloride-d ) δ 150.58, 143.30,
2
141.35, 141.11, 136.76, 133.78, 133.14, 132.72, 132.22, 131.98,
130.78, 130.71, 128.43, 127.00, 126.82, 125.91, 125.69, 124.99,
121.25, 119.09, 117.11, 117.04, 114.56, 38.03, 36.40, 33.02, 31.32.
was evaporated under reduced pressure to give a yellow oil, which was
redissolved in CH Cl (10 mL), followed by the sequential addition
of iodine (135 mg, 0.532 mmol) and K CO (185 mg, 1.34 mmol).
2
2
+
•
+•
2
3
HRMS (EI) m/z [M ] calcd for [C H N ] , 517.25180; found,
37 31 3
The reaction mixture was stirred at reflux temperature for another 16
h. Upon completion of the reaction, it was quenched with 5%
Na S O (20 mL) and then extracted with CH Cl (10 mL × 3). The
517.25084; difference, −1.86 ppm.
Synthesis of 1-[4-(9H-Carbazol-9-yl)phenyl]-6,6-dimethyl-6H-
imidazo[4,5,1-de]acridine (CZ-IMAC). A mixture of 5 (100 mg,
0.446 mmol) and 4-(9H-carbazol-9-yl)benzaldehyde (135 mg, 0.498
mmol) in EtOH (10 mL) was refluxed for 16 h. The solvent was
evaporated under reduced pressure to give a yellow oil, which was
2
2
3
2
2
combined organic layer was washed with brine (20 mL), dried over
anhydrous MgSO , concentrated, and then purified through silica gel
4
column chromatography (1:1, hexanes:CH Cl , R = 0.25) to afford a
2
2
f
yellow/green solid. Yield = 136 mg (62%). X-ray quality crystals were
redissolved in CH
of iodine (135 mg, 0.532 mmol) and K
The reaction mixture was stirred at reflux temperature for the 16 h.
Upon completion of the reaction, it was quenched with 5% Na
(20 mL) and then extracted with CH Cl (10 mL × 3). The
combined organic layer was washed with brine (20 mL), dried over
anhydrous MgSO , concentrated, and then purified through silica gel
column chromatography (1% MeOH in CH Cl , R = 0.20) to afford
a light pink solid. The solid was dissolved in a minimal amount of
CH Cl and layered with hexane to give large X-ray quality crystals of
CZ-IMAC. Yield = 118 mg (56%). mp = 254.1−255.8 °C. H NMR
(400 MHz, DMSO-d ) δ 8.33 (d, J = 7.8 Hz, 2H), 8.13 (d, J = 8.1 Hz,
2
Cl
2
(10 mL), followed by the sequential addition
obtained from the slow evaporation of a solution of PXZ-IMAC in
2
CO (185 mg, 1.34 mmol).
3
1
CH Cl /hexanes. mp = 221.2−223.1 °C. H NMR (400 MHz,
2
2
methylene chloride-d ) δ 8.14−8.06 (m, 2H), 7.69 (ddd, J = 18.5, 7.8,
S O
2 2 3
2
1
2
6
.4 Hz, 2H), 7.64−7.59 (m, 2H), 7.51−7.36 (m, 2H), 7.34−7.23 (m,
H), 7.14 (ddd, J = 8.5, 7.4, 1.5 Hz, 1H), 6.83−6.65 (m, 6H), 6.24−
2
2
1
3
.10 (m, 2H), 1.82 (s, 6H). C NMR (101 MHz, methylene
4
chloride-d ) δ 150.36, 144.39, 141.29, 140.98, 136.75, 134.44, 133.71,
2
2
f
2
1
33.40, 132.88, 131.95, 131.73, 130.72, 128.43, 126.99, 125.90,
1
25.01, 123.76, 122.01, 119.12, 117.08, 116.95, 115.85, 113.82, 38.01,
2.98. HRMS (EI) m/z [M ] calcd for [C H N O ] , 491.19976;
2
2
+•
+•
1
3
34 25 3 1
found, 491.19866; difference, −2.24 ppm.
6
Synthesis of 10-[4-(6,6-Dimethyl-6H-imidazo[4,5,1-de]acridin-1-
2H), 7.93 (d, J = 8.1 Hz, 2H), 7.68−7.59 (m, 3H), 7.59−7.47 (m,
yl)phenyl]-10H-phenothiazine (PTZ-IMAC). A mixture of 5 (100 mg,
3H), 7.44 (t, J = 7.7 Hz, 1H), 7.38 (t, J = 7.4 Hz, 2H), 7.33−7.19 (m,
1
3
0
0
.446 mmol) and 4-(10H-phenothiazin-10-yl)benzaldehyde (149 mg,
.491 mmol) in EtOH (10 mL) was refluxed for 16 h. The solvent
3H), 1.77 (s, 6H). C NMR (101 MHz, DMSO-d ) δ 149.69,
6
140.25, 139.85, 138.49, 135.84, 132.69, 131.39, 131.06, 130.78,
130.10, 128.36, 127.03, 126.87, 126.45, 125.67, 124.64, 123.02,
120.64, 120.45, 118.90, 116.40, 116.06, 109.82, 37.28, 32.62. HRMS
was evaporated under reduced pressure to give a reddish oil, which
was redissolved in CH Cl (10 mL), followed by the sequential
2
2
+
•
+•
addition of iodine (135 mg, 0.532 mmol) and K CO (185 mg, 1.34
(EI) m/z [M ] calcd for [C H N ] , 475.20485; found,
2
3
34 25 3
mmol). The reaction mixture was stirred at reflux temperature for
another 16 h. Upon completion of the reaction, it was quenched with
475.20331; difference, −3.24 ppm.
Synthesis of 1-[4-(9′H-[9,3′:6′,9″-tercarbazol]-9′-yl)phenyl]-6,6-
dimethyl-6H-imidazo[4,5,1-de]acridine (TerCZ-IMAC). A mixture of
5 (58.0 mg, 0.259 mmol) and 4-(9’H-[9,3′:6′,9″-tercarbazol]-9′-
yl)benzaldehyde (170 mg, 0.283 mmol) in EtOH (10 mL) and 1,2-
dichloroethane (10 mL) was refluxed for 16 h. The solvent was
evaporated under reduced pressure to give a reddish oil, which was
redissolved in 1,2-dichloroethane (10 mL), followed by the sequential
addition of iodine (92 mg, 0.36 mmol) and K CO (108 mg, 0.781
5
% Na S O (20 mL) and then extracted with CH Cl (10 mL × 3).
2 2 3 2 2
The combined organic layer was washed with brine (20 mL), dried
over anhydrous MgSO , concentrated, and then purified through silica
4
gel column chromatography (CH Cl , R = 0.15) to afford a yellow
2
2
f
solid. Yield = 148 mg (65%). X-ray quality crystals were obtained
from the slow evaporation of a solution of PTZ-IMAC in CH Cl /
2
2
1
hexanes. mp = 259.8−261.1 °C. H NMR (400 MHz, methylene
2
3
chloride-d ) δ 8.05−7.97 (m, 2H), 7.70 (dd, J = 7.9, 1.5 Hz, 1H), 7.66
mmol). The reaction mixture was stirred at reflux temperature for
another 16 h. Upon completion of the reaction, it was quenched with
5% Na S O (20 mL) and then extracted with CH Cl (10 mL × 3).
2
(
7
6
dd, J = 7.7, 1.1 Hz, 1H), 7.60−7.53 (m, 2H), 7.48−7.38 (m, 2H),
.35 (dd, J = 8.3, 1.3 Hz, 1H), 7.30−7.20 (m, 3H), 7.12 (tdd, J = 7.8,
.0, 1.6 Hz, 3H), 7.02 (td, J = 7.5, 1.3 Hz, 2H), 6.74 (dd, J = 8.1, 1.3
2
2
3
2
2
The combined organic layer was washed with brine (20 mL), dried
1
3
Hz, 2H), 1.82 (s, 6H). C NMR (101 MHz, methylene chloride-d2)
δ 150.70, 144.10, 143.82, 141.32, 136.71, 133.83, 132.22, 131.99,
over anhydrous MgSO , concentrated, and then purified through silica
4
gel column chromatography (CH Cl , R = 0.25) to afford an off-
2
2
f
1
1
1
31.22, 130.66, 128.34, 127.84, 127.66, 127.48, 126.97, 125.82,
24.92, 124.28, 123.97, 119.31, 118.96, 117.01, 116.99, 38.00, 32.93.
white solid. Yield = 131 mg (58%). mp = 243.5−245.4 °C. H NMR
(400 MHz, methylene chloride-d ) δ 8.35 (d, J = 2.0 Hz, 2H), 8.23−
2
G
DOI: 10.1021/acs.joc.9b02283
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
8
.14 (m, 6H), 8.03−7.97 (m, 2H), 7.88 (d, J = 8.7 Hz, 2H), 7.74−
.63 (m, 4H), 7.49−7.37 (m, 11H), 7.28 (m, 5H), 7.18 (m, 1H), 1.81
(s, 12H). 13C NMR (101 MHz, benzene-d ) δ 147.18, 140.92, 137.50,
6
7
130.82, 130.06, 126.24, 124.75, 123.11, 119.19, 111.75, 20.72. HRMS
s, 6H) ppm. 13C NMR (101 MHz, methylene chloride-d ) δ 150.55,
(EI) m/z [M ] calcd for [C H N ] , 557.28310; found,
+•
+•
(
2
40 35 3
1
1
1
1
42.32, 141.46, 140.97, 139.33, 137.01, 133.97, 132.86, 132.25,
31.24, 130.98, 128.66, 127.78, 127.32, 126.90, 126.51, 126.19,
25.29, 124.91, 123.69, 120.78, 120.32, 120.30, 119.39, 117.29,
557.28241; difference, −1.23 ppm.
4-{3,6-Bis[di(p-tolyl)amino]-9H-carbazol-9-yl}benzaldehyde
(S3). S2 (500 mg, 0.896 mmol), K PO (1.00 g, 4.50 mmol) and
DMF (33 mL) were combined in a 100 mL round-bottom flask
equipped with a magnetic stir bar and reflux condenser. The reaction
was heated to 150 °C before addition of 4-fluorobenzaldehyde (0.30
mL, 2.70 mmol). After stirring for 16 h the reaction mixture was
3
4
+•
17.24, 112.06, 110.29, 38.24, 33.14 ppm. HRMS (EI) m/z [M ]
+•
calcd for [C H N ] , 805.32055; found, 805.31727; difference,
−
58
39
5
3.28 ppm.
Synthesis of 9-[4-(6,6-Dimethyl-6H-imidazo[4,5,1-de]acridin-1-
3
3
6
6
yl)phenyl]-N ,N ,N ,N -tetra(p-tolyl)-9H-carbazole-3,6-diamine
TolCZ-IMAC). A mixture of 5 (74.0 mg, 0.330 mmol) and 4-[3,6-
bis(di-p-tolylamino)-9H-carbazol-9-yl]benzaldehyde (S3) (300 mg,
.453 mmol) in EtOH (10 mL) and 1,2-dichloroethane (10 mL) was
allowed to cool to room temperature, filtered to remove K PO , and
3 4
(
concentrated under reduced pressure. The brown mixture was
purified through silica gel column chromatography (hexanes/
CH Cl 1:1, R = 0.15) to afford a bright yellow solid. Yield = 340
0
2
2
f
1
refluxed for 16 h. The solvent was evaporated under reduced pressure
to give a reddish oil, which was redissolved in 1,2-dichloroethane (10
mL), followed by the sequential addition of iodine (117 mg, 0.461
mmol) and K CO (137 mg, 0.991 mmol). The reaction mixture was
mg (48%). mp = 141.1−143.0 °C. H NMR (400 MHz, benzene-d )
6
δ 9.66 (s, 1H), 7.83 (d, J = 2.1 Hz, 2H), 7.56−7.49 (m, 2H), 7.29
(dd, J = 8.8, 2.1 Hz, 2H), 7.17 (m, 4H), 7.16−7.08 (m, 8H), 6.93 (d,
1
3
J = 8.2 Hz, 8H), 2.11 (s, 12H). C NMR (101 MHz, benzene-d ) δ
2
3
6
stirred at reflux temperature for another 16 h. Upon completion of the
189.97, 146.94, 143.01, 142.42, 137.71, 134.96, 131.29, 131.19,
130.16, 126.40, 126.33, 125.46, 123.32, 118.79, 111.13, 20.73. HRMS
reaction, it was quenched with 5% Na S O (20 mL) and then
2
2
3
+
•
+•
extracted with EtOAc (10 mL × 3). The combined organic layer was
washed with brine (20 mL), dried over anhydrous MgSO4,
concentrated, and then purified through silica gel column
chromatography (1:1, hexanes:CH Cl , R = 0.30) to afford a green
(EI) m/z [M ] calcd for [C H N O] , 661.30931; found,
47 39 3
661.30651; difference, −4.24 ppm.
52
4-(9,9-Dimethyl-10(9H)-acridinyl)benzaldehyde (S4). To a 3-
neck, 3 L round-bottom flask was added acridine (26.0 g, 124 mmol),
2
2
f
1
solid. Yield = 170 mg (60%). mp = 193.4−195.6 °C. H NMR (400
K PO (132 g, 621 mmol), and 2.15 L of DMF as well as a magnetic
3 4
MHz, benzene-d ) δ 8.04−7.97 (m, 3H), 7.94−7.88 (m, 2H), 7.48−
stir bar. A reflux condenser was attached to the flask, then the reaction
mixture was heated to reflux. Once refluxing, 4-fluorobenzaldehyde
(26.7 mL, 248 mmol) was added to the reaction mixture gradually.
The reaction mixture was stirred overnight. After confirmation of the
completion of the reaction by TLC, the crude reaction mixture was
6
7
.29 (m, 17H), 7.10−6.98 (m, 9H), 2.24 (s, 12H), 1.68 (s, 6H) ppm.
1
3
C NMR (101 MHz, benzene-d ) δ 150.52, 147.05, 142.18, 142.03,
6
1
1
1
3
8
39.41, 138.19, 136.47, 134.12, 132.34, 131.81, 131.65, 131.12,
30.13, 128.38, 128.14, 127.91, 126.79, 126.62, 126.43, 125.47,
25.24, 125.14, 123.26, 118.91, 118.80, 117.92, 117.09, 111.31, 37.76,
filtered to remove excess K PO . The filtrate was then concentrated
3
4
+•
+•
under reduced pressure then dissolved in 500 mL ethyl acetate. This
organic layer was washed three times with 250 mL of deionized water,
2.48, 20.74 ppm. HRMS (EI) m/z [M ] calcd for [C H N ] ,
6
2
51
5
65.41445; found, 865.41440; difference, −0.04 ppm.
3
3
6
6
dried over MgSO , filtered and concentrated under reduced pressure.
9
-Benzyl-N ,N ,N ,N -tetra(p-tolyl)-9H-carbazole-3,6-diamine
S1). Ditolylamine (11.7 g, 59.0 mmol), 9-benzyl-3,6-diiodo-9H-
carbazole (10.0 g, 19.8 mmol), K CO (21.7 g, 157.0 mmol), Cu
4
(
The crude mixture was purified by column chromatography using a
gradient of hexane and CH Cl (100% hexane to 100% CH Cl ) on
2
3
2 2 2 2
1
powder (5.07 g, 79.7 mmol), and 18-crown-6 (1.04 g, 3.93 mmol)
were added to a flame-dried 500 mL round-bottom flask equipped
with a magnetic stir bar and reflux condenser. The vessel was
silica. Yield = 38.3 g (98%). H NMR (400 MHz, chloroform-d) δ
10.16 (s, 1H), 8.17 (d, J = 8.4 Hz, 2H), 7.58 (d, J = 8.3 Hz, 2H),
7.55−7.49 (m, 2H), 7.03 (m, 4H), 6.42−6.35 (m, 2H), 1.73 (s, 6H).
1
3
evacuated and refilled with N three times before addition of dry,
C NMR (101 MHz, chloroform-d) δ 191.18, 147.47, 140.37,
2
degassed o-dichlorobenzene (150 mL). The reaction mixture was
heated to reflux and left stirring for 120 h. The reaction mixture was
allowed to cool to room temperature, filtered to remove K CO , and
2
3
concentrated under reduced pressure. The brown residue was
dissolved in CH Cl and washed with water three times. The organic
2
2
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.joc.9b02283.
■
layer was collected, dried with MgSO , filtered and concentrated
4
S
*
under reduced pressure. The solid was dissolved in CH Cl and
2
2
further purified by reprecipitation into hexanes (three times) to afford
1
a yellow powder. Yield = 11.65 g (91%). mp = 132.4−134.2 °C. H
NMR (400 MHz, DMSO-d ) δ 7.81 (d, J = 2.1 Hz, 2H), 7.59 (d, J =
X-ray crystallography details for PXZ-IMAC (CIF)
X-ray crystallography details for PTZ-IMAC (CIF)
X-ray crystallography details for ACR-IMAC (CIF)
X-ray crystallography details for CZ-IMAC (CIF)
Synthetic schemes for compounds S1−S4; 1H and
6
8
.8 Hz, 2H), 7.37−7.20 (m, 5H), 7.15 (dd, J = 8.7, 2.2 Hz, 2H), 7.01
(d, J = 8.1 Hz, 8H), 6.91−6.72 (m, 8H), 5.61 (s, 2H), 2.22 (s, 12H).
13
C NMR (101 MHz, DMSO-d ) δ 145.93, 139.50, 137.76, 130.25,
6
1
1
6
29.66, 128.63, 127.35, 126.89, 125.44, 122.87, 122.06, 118.32,
+•
+•
10.64, 45.89, 20.24. HRMS (EI) m/z [M ] calcd for [C H N ] ,
4
7
41
3
13
1
C{ H} NMR spectra of all compounds, solvatochromic
47.33005; found, 667.32831; difference, −2.68 ppm.
3
3
6
6
N ,N ,N ,N -Tetra(p-tolyl)-9H-carbazole-3,6-diamine (S2). AlCl
properties, nanosecond PL decay curves, and cyclic
voltammograms of all IMAC compounds (PDF)
3
(
16.8 g, 126.0 mmol) was suspended in dry, degassed anisole (15 mL)
and cooled to 0 °C with stirring. In a separated flask S1 (11.7 g, 18.0
mmol) was taken up in anisole (50 mL) and then transferred into the
AUTHOR INFORMATION
Corresponding Authors
E-mail: yamaguchi@chem.nagoya-u.ac.jp. Tel: +1-604-822-
3266. Fax: +1-604-822-2847.
*E-mail: zhudson@chem.ubc.ca.
■
*
AlCl solution, resulting in a color change from yellow to dark brown.
3
Upon heating the reaction to 70 °C the reaction became clear. After
1
6 h the reaction mixture was poured into water (250 mL) and
extracted with toluene (3 × 50 mL). The organic layers were
collected, dried over MgSO , filtered and concentrated under reduced
4
pressure. The mixture was purified through silica gel column
chromatography (hexanes/CH Cl 2:1, R = 0.25) to afford an off-
ORCID
2
2
f
1
Ethan R. Sauve: 0000-0002-0779-6465
́
Shigehiro Yamaguchi: 0000-0003-0072-8969
Zachary M. Hudson: 0000-0002-8033-4136
white solid. Yield = 8.33 g (83%). mp = 258.9−260.8 °C. H NMR
400 MHz, benzene-d ) δ 7.77 (d, J = 2.1 Hz, 2H), 7.32 (dd, J = 8.6,
(
6
2.1 Hz, 2H), 7.16−7.10 (m, 8H), 6.91 (m, 10H), 6.44 (s, 1H), 2.11
H
DOI: 10.1021/acs.joc.9b02283
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
Notes
(14) Sharma, N.; Spuling, E.; Mattern, C. M.; Li, W.; Fuhr, O.;
̈
Tsuchiya, Y.; Adachi, C.; Brase, S.; Samuel, I. D. W.; Zysman-Colman,
The authors declare no competing financial interest.
E. Turn on of Sky-Blue Thermally Activated Delayed Fluorescence
and Circularly Polarized Luminescence (CPL) via Increased Torsion
by a Bulky Carbazolophane Donor. Chem. Sci. 2019, 10, 6689−6696.
ACKNOWLEDGMENTS
■
(15) Kawasumi, K.; Wu, T.; Zhu, T.; Chae, H. S.; Van Voorhis, T.;
The authors thank the Natural Sciences and Engineering
Research Council of Canada (NSERC), the Canada
Foundation for Innovation (CFI), the British Columbia
Knowledge Development Fund (BCKDF), and the University
of British Columbia (UBC) for support of their research
program. ERS thanks NSERC for a Postgraduate Scholarship
and the Mitacs-Japan Society for the Promotion of Science
Baldo, M. A.; Swager, T. M. Thermally Activated Delayed
Fluorescence Materials Based on Homoconjugation Effect of
Donor−Acceptor Triptycenes. J. Am. Chem. Soc. 2015, 137, 11908−
1
(
1911.
16) Tsujimoto, H.; Ha, D.-G.; Markopoulos, G.; Chae, H. S.; Baldo,
M. A.; Swager, T. M. Thermally Activated Delayed Fluorescence and
Aggregation Induced Emission with Through-Space Charge Transfer.
J. Am. Chem. Soc. 2017, 139, 4894−4900.
(17) Liu, Y.; Li, C.; Ren, Z.; Yan, S.; Bryce, M. R. All-Organic
Thermally Activated Delayed Fluorescence Materials for Organic
Light-Emitting Diodes. Nat. Rev. Mater. 2018, 3, 18020.
(
JSPS) summer program, and ZMH is also grateful for support
from the Canada Research Chairs program. The authors thank
Dr. Saeid Kamal for his generous help in measuring time-
resolved spectra.
(18) Hirai, H.; Nakajima, K.; Nakatsuka, S.; Shiren, K.; Ni, J.;
Nomura, S.; Ikuta, T.; Hatakeyama, T. One-Step Borylation of 1,3-
Diaryloxybenzenes Towards Efficient Materials for Organic Light-
Emitting Diodes. Angew. Chem., Int. Ed. 2015, 54, 13581−13585.
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